The present invention is directed to a telescopic tool for stripping waste from a sheet processing machine, which tool includes a cylindrical body having a pin extending from one end of the body. The cylindrical body has a first bore which forms an internal shoulder with a second smaller bore and the pin has two end portions separated by a collar. The pin is received in the first and second bore with the collar being biased by a spring acting between a cap closing the first bore against the shoulder with one portion of the pin extending out of the second bore. The cap includes a bore or passage for guiding the other end of the pin as it is shifted from a position with the collar engaging the shoulder to an inward position.
A telescopic tool of this type is known to the users as currently utilized for stripping waste from sheets being processed in a machine, such as a board sheet cutter.
In a waste stripping station of a cutting press, the tools are fitted on upper and lower frames consisting of movable crossbars in such a way as to be set according to the position of the waste. Such a use is shown by U.S. Pat. No. 3,784,070, whose disclosure is incorporated herein by reference thereto and which corresponds to German Patent No. 2,158,907.
Generally, these frames are imparted with a vertical reciprocal movement destined to apply the points of the upper and lower pins of the tools onto the surface of the waste so as to pinch the waste between the ends during a first stage of operation. During a second stage, the pair of pins move the waste downward to a plane different from that of the sheet so as to strip the waste from the sheet and then the pins separate to drop the waste as the frames move back to the original position to withdraw the pins from the sheet being processed. During the course of this stripping action, the pins will move to and fro within the hollow cylindrical body. Also during this stripping process, the conveyors of the press are in a dwell period and hold the sheet in a fixed position in the stripping station. Then, as the process is completed, the conveyors will move the sheet stripped of its waste to the next station as the next sheet to be stripped is moved into the stripping station.
The sheets generally contain a large number of waste bits, for which reason the upper and lower frames are equipped with an adequate number of telescopic tools. Conspicuously, the assembly comprising the frames and the tools represent a certain mass with considerable inherent inertia in case of high-speed presses used in this field, so that the press will be powered accordingly.
Up to now, the hollow cylindrical body has been made out of aluminum or aluminum alloy and the pins have been constructed of steel.
The use of such telescopic tools fitted on their upper and lower frames involves numerous drawbacks with production speeds of the press being further increased. The first of these drawbacks is the noise that results from the impact of the steel pins on the waste. The second drawback is the blunting of the pin points or ends which, in the event of advanced wear, will cause the pins to be squeezed or shifted laterally in the bores machined in the hollow cylindrical bodies to decrease the amount of pressure exerted by the pin points on the waste. It has effectively been noticed that in the course of production runs, the pin points could wear as far as to take on an oblique plane. In certain cases, the pins even break due to the lateral stresses caused by the wearing of their points.
The oblique wearing of the pin point can be caused either by an inadequate positioning of the upper pin with regard to the lower one or by an inaccurate fitting of the tool on the frame. For example, the tool being slightly obliquely arranged on the frame.
A third drawback consists in the heavy structure of every telescopic tool compelling the designer of the cutting press to adopt a largely dimensioned drive assembly, which arrangement will have a negative influence on the wanted increase in the production speed.